For the production of non-amino-organic acids including succinic acid by fermentation, anaerobic bacteria including those belonging to the genus Anaerobiospirillum or Actinobacillus are usually used (U.S. Pat. Nos. 5,142,834 and 5,504,004, and International Journal of Systematic Bacteriology (1999), 49, 207-216). Although the yield of products is high by using such anaerobic bacteria, many nutrients are required for their proliferation, and therefore, it is necessary to add a large amount of organic nitrogen sources such as corn steep liquor (CSL) into a culture medium. The addition of large amount of organic nitrogen sources not only leads to an increase in the culture cost but also an increase in purification cost for isolating the product, therefore it is not economical.
In addition, methods in which aerobic bacteria such as coryneform bacteria are cultured under aerobic conditions to proliferate bacterial cells and then harvested and washed to allow them as resting cells to produce non-amino organic acid without oxygen aeration, have been known (JP11-113588A and JP11-196888A). These methods are economical because bacteria can grow sufficiently in a simple culture medium containing less amount of organic nitrogen for proliferating bacterial cells. However, there is still a desire for improvement in terms of production amount, concentration, and production rate of the target organic acids per bacterial cell as well as simplification of production process, and so on.
In the case of producing non-amino organic acids by fermentation, pH decreases along with generation of the non-amino organic acids, so that it is necessary to perform the reaction while adjusting pH by neutralization. So far, sodium carbonate, ammonium carbonate, or the like has been used for adjusting pH, but there has been a problem that the volume of the reaction solution increases by addition of a neutralizing solution. Meanwhile, because magnesium carbonate and magnesium hydroxide are difficult to be dissolved in water, they have not been used for adjusting the pH in production of non-amino organic acids by fermentation using coryneform bacteria.